In silico investigation of the effects of hemolysis on the hyperspectral absorptance of blood in motion.

Measurement of the optical absorptance of blood can provide insight into its composition and behaviour. Accordingly, optical devices and sensors are commonly used in a clinical setting to measure the absorptance of blood, either directly or indirectly through measurement of skin spectral responses. These measurements enable the evaluation or constant monitoring of a patient's blood. In this paper, we perform predictive simulations to investigate the absorptance of blood and how it is affected by hemolysis. These simulations are performed using a cell-based light interaction model, known as CLBlood, which accounts for the orientation and distribution of red blood cells. This allows us to evaluate the effect of hemolysis under different flow conditions. Furthermore, we produce results in the ultraviolet, visible and infrared domains using CLBlood's hyperspectral capabilities. We then evaluate the sensitivity of the absorptance signature of blood to hemolysis in each of these domains under several experimental conditions. The observations in this paper enhance our understanding of the impact of hemolysis on the optical absorptance of blood, potentially leading to simplified and more accurate methods for its detection and monitoring.

Three-wavelength method for the optical differentiation of methemoglobin and sulfhemoglobin in oxygenated blood.

Methemoglobinemia and sulfhemoglobinemia are rare, but potentially life threatening, diseases that refer to an abnormal amount of methemoglobin or sulfhemoglobin in the blood, respectively. Unfortunately, blood samples containing abnormal quantities of methemoglobin or sulfhemoglobin have similar spectral characteristics. This makes it difficult to optically differentiate them and, hence, difficult to diagnose a patient with either disease. However, performing treatments for one of the diseases without a correct diagnosis can introduce increased risk to the patient. In this paper, we propose a method for differentiating the presence of methemoglobin and sulfhemoglobin in blood, under several conditions, using reflectance values measured at three wavelengths. In order to validate our method, we perform in silico experiments considering various levels of methemoglobin and sulfhemoglobin. These experiments employ a cell-based light interaction model, known as CLBlood, which accounts for the orientation and distribution of red blood cells. We then discuss the reflectance curves produced by the experiments and evaluate the efficacy of our method. In particular, we consider various experimental conditions by modifying the flow rate, hemolysis level and incident light direction.

On the noninvasive optical monitoring and differentiation of methemoglobinemia and sulfhemoglobinemia.

There are several pathologies whose study and diagnosis is impaired by a relatively small number of documented cases. A practical approach to overcome this obstacle and advance the research in this area consists in employing computer simulations to perform controlled in silico experiments. The results of these experiments, in turn, may be incorporated in the design of differential protocols for these pathologies. Accordingly, in this paper, we investigate the spectral responses of human skin affected by the presence of abnormal amounts of two dysfunctional hemoglobins, methemoglobin and sulfhemoglobin, which are associated with two life-threatening medical conditions, methemoglobinemia and sulfhemoglobinemia, respectively. We analyze the results of our in silico experiments and discuss their potential applications to the development of more effective noninvasive monitoring and differentiation procedures for these medical conditions.

A novel approach for simulating light interaction with particulate materials: application to the modeling of sand spectral properties.

In this paper, we present a new spectral light transport model for sand. The model employs a novel approach to simulate light interaction with particulate materials which yields both the spectral and spatial (bi-directional reflectance distribution function, or BRDF) responses of sand. Furthermore, the parameters specifying the model are based on the physical and mineralogical properties of sand. The model is evaluated quantitatively, through comparisons with measured data. Good spectral reconstructions were achieved for the reflectances of several real sand samples. The model was also evaluated qualitatively, and compares well with descriptions found in the literature. Its potential applications include, but are not limited to, applied optics, remote sensing and image synthesis.